R1:959bb16d0f67

Allow Almanac services to be searched by substring

Summary: Ref T10246. Build an ngram index for Almanac services, and use it to support improved search.

Test Plan: {F1121725}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10246

Differential Revision: https://secure.phabricator.com/D15321